Aldol condensation is an organic reaction in which an enol or an enolate ion reacts with a carbonyl compound to form a β-hydroxyaldehyde or β-hydroxyketone, followed by a dehydration to give a conjugated enone. Specifically, the first part of the aldol condensation reaction is an aldol reaction and the second part is an elimination reaction (e.g., dehydration that involves removal of a water molecule or an alcohol molecule). Because β-hydroxyaldehydes, β-hydroxyketones, and enones have long been valued commercially, many methods of production have been developed. One exemplary aldol condensation production process utilizes the catalyzed condensation of acetone or dimethyl ketone (DMK) to obtain diacetone alcohol (DAA), and the dehydration of the DAA to yield mesityl oxide (MO). DAA is an industrially important compound that is mainly used as a solvent in purification processes. MO is a useful compound with various applications, including its use as a precursor to the industrial solvent, methyl isobutyl ketone (MIBK).
Aldol condensation reactions are often conducted in the presence of a catalyst composition. For example, the aldol condensation of acetone is commonly conducted in the presence of a base catalyst composition comprising an active phase including NaOH, KOH, Ca(OH)2, and/or Ba(OH)2. Many other alternative catalyst active phases exist such as metal oxides and hydroxides, which exhibit both acidic and basic properties, with varying degrees of selectivity towards DAA. Furthermore, the catalyst composition commonly includes at least one of the aforementioned active phases affixed to a support formed from carbon, alumina, and/or sodium metasilicate. However, these catalyst compositions can be expensive and have been known to exhibit only low to moderate conversion and regeneration when used in aldol condensation reactions.
Thus, the need exists for improved processes for performing low cost aldol condensation reactions, and for improved catalysts capable of providing high enol or enolate ion conversions in the formation of β-hydroxyaldehydes or β-hydroxyketones, and high selectivity for β-hydroxyaldehydes, β-hydroxyketones, and/or conjugated enones.